I would more say its not fair to compare windows 98/ME.. Too me XP is still mainstream sure its getting to EOL but of course there will be the masses that still use it..
For video capture drivers I found that it really doesn't matter if its Linux or Windows, it can a pain to actually get drivers and to actually have them working flawlessly on either platform.. It all depends on how popular the card is and the platforms it supports. Well for linux is more about supported chipsets..
